Particulate matter is suspended in air or other gas streams in many different industries and, in many instances, the particulate matter needs to be removed from the gas streams. Systems for cleaning a gas stream laden with particulate matter include air filter systems having filter elements located in a housing. The filter element may be in the form of a bag or sock of a suitable fabric or pleated paper. The gas stream, contaminated with particulate, typically is passed through the housing so that the particulate are captured and retained by the filter element. Cleaning is accomplished, in some systems, by periodically pulsing a brief j et of pressurized air into the interior of the filter element to reverse the air flow through the filter element, causing the collected contaminants to be collected. Examples of such air filter systems are disclosed in, for example, U.S. Pat. No. 4,218,227 (Frey) and U.S. Pat. No. 4,395,269 (Schuler).
In a common design, an air filter system has a clean air chamber and a dirty air chamber. The two chambers are separated by a sheet metal, commonly referred to as a tube sheet. The tube sheet has a number of openings over which filter elements are placed. Particulate-laden air is introduced into the dirty air chamber, and the particulates collect onto the filter elements as the air moves through the openings in the tube sheet from the dirty air chamber into the clean air chamber. From the clean air chamber, the cleaned air is exhausted into the environment, or recirculated for other uses. For example, U.S. Pat. No. 4,424,070 (Robinson), U.S. Pat. No. 4,436,536 (Robinson), U.S. Pat. No. 4,443,237 (Ulvestad), U.S. Pat. No. 4,445,915 (Robinson), U.S. Pat. No. 5,207,812 (Tronto et al.), U.S. Pat. No. 4,954,255 (Muller et al.), U.S. Pat. No. 5,222,488 (Forsgren), U.S. Pat. No. 5,211,846 (Kott et al.), U.S. Pat. No. 5,730,766 (Clements), U.S. Pat. No. 4,661,131 (Howeth), U.S. Pat. No. 6,488,746 (Kosmider et al.), and U.S. Pat. No. 8,128,724 (Mills et al.) disclose examples of a variety of filter element designs.